Hello, I have a guys 2001 Dodge that is losing about two to three quarts of oil out the breather tube in 50 miles.  This tube comes out the side of the lifter/pushrod cover.  The truck runs fine and is not underpowered but there is also a good deal of blow by coming out the oil fill at the rocker cover.  Right off the bat I’m thinking bad rings but I’ve read some other forums that said a bad vacuum pump could cause this also.  It started happening all of a sudden which causes me concern that it might be a vacuum pump if that can cause it.  Thoughts?

Plug the vacuum line coming out of the vacuum pump just below the  VP, if it helps then you have a vacuum leak somewhere. I'd have to say there's nothing wrong with your vacuum pump if anything it's actually good, being it's creating vacuum and shoving it in the crankcase. unless it's leaking between power steering pump and vacuum pump then you need a new seal kit. 

Beyond that. If you do everything @Dieselfuture mentions then...

 

Valve seals failed, excessive valve guide clearance.

Broken or wore out piston ring(s), piston damage or excessive piston clearance.

Cracked head or bad head gasket.

Ok, this morning I zip tied an empty water bottle to the end of the crankcase draft tube so tube would drain into the bottle.  Went on a 12 mile road test.  It filled that bottle a third with engine oil.  The next road test, same mileage, only a half in of oil in the bottle.  The next two road tests, one with the vacuum line disconnected from the vacuum pump, no oil at all in the bottle.  This engine has a lot of crankcase pressure.  It is a bone stock engine.  I was leaning toward the vacuum pump but not sure now.  Truck has 300,000 on the clock.

Sounds like a massive vacuum leak if the vacuum pump was disconnected and capped and no oil.

3 hours ago, WesHawkins said:

The next two road tests, one with the vacuum line disconnected from the vacuum pump, no oil at all in the bottle.

Assuming you put a cap on the pump, then yes you have a vacuum leak somewhere. Vacuum pump constantly draws air into the crankcase if you have no vacuum leaks it doesn't really suck any air just creates vacuum for vacuum operating things, like HVAC system, cad if you have one. But if you have a vacuum leak it just keeps pumping air to the crankcase, it has to go somewhere.

This truck has 297,623 miles on it and it has not been well cared for.  It lives in a hostel environment if constant dirt, mud and snow.  I’m going to do a compression and leak down test also so I can give the owner as complete a diagnosis I can.  With the condition of this truck it could be an all of the above.

Do a compression test would work too. 

 

I'm not a fan of blow by test being it is possible to have only one cylinder with issues and pass.

2 hours ago, Mopar1973Man said:

Do a compression test would work too. 

 

I'm not a fan of blow by test being it is possible to have only one cylinder with issues and pass.

   I’ve got the injectors out but the kit I purchased two months ago doesn’t have the adapter for the Dodge Cummings so I’m waiting for that adapter to show up.  Probably tomorrow.

Compression test will show the bad cylinder much quicker. We had a old member with a cracked piston that would pass the blow by test but as the truck warmed up the misfire would get worse. He never did a compression test but ended up replacing the entire engine over a cracked piston. 

41 minutes ago, Mopar1973Man said:

Compression test will show the bad cylinder much quicker. We had a old member with a cracked piston that would pass the blow by test but as the truck warmed up the misfire would get worse. He never did a compression test but ended up replacing the entire engine over a cracked piston. 

  Haven’t looked at it in two days, had to evacuate because of a fire plus I just got the adapter to use for the compression test.  This thing doesn’t come close to passing the blow by test.  

59 minutes ago, WesHawkins said:

This thing doesn’t come close to passing the blow by test.  

 

Well... All I can say is rebuild time. If its got that much blow by then the engine should be rebuilt. Either the engine was dusted out by a washable filter or bad injectors washing out the rings. Could be head gasket blown to the push rod hole too. I've seen cracked heads pressurize either the fuel tank (cracked to the return rail) or the crankcase. Compression test would tell the story of whats going on.

Edited August 6, 20213 yr by Mopar1973Man

  Well after being evacuated for two days I’m back out in the shop working on this poor truck.  Compression tells the story I think.  #1 cyl, 260psi, #2 cyl, 300psi, #3 cyl, 290psi, cyl 4, 5 &6 320 psi.  If the two really weak cylinders were next to each other I might look at it being a head gasket but I think she’s just worn out.

All are low. Normally these engines are 400 to 450 PSI. The rings are wasted and the bores most likely need to be sleeved.

@Mopar1973Man, you don't think the block could be bored? Cummins sells .020 and .040 overbore pistons.   

Oh I know it can be bored oversized it just if the current sleeves are shot most just bore it out and re-sleeve. Not many are in for larger power that is a very small percentage which I deal with. 

I didn't think our trucks were sleeved? 

Me neither...

 

- John

   I had read some other forums where guys were saying the vacuum pump could cause excessive blow by by pressuring the the backside and into the crankcase but this is vein style pump and I looked at a new/rebuilt unit this morning and don’t see how that can happen unless it pushes back through the oil lubrication return.  Two years ago it grenaded the turbo and I replaced it and cleaned the inner cooler and all the intake pipes.  It most likely ingested bits and pieces and he’s seeing the results of that now.
  We’ll see what this guy wants to do.   The overall condition this truck is in it’s not worth a rebuild. He could buy a used truck and be way ahead of the game.